Control for refrigerating systems



2 Sheets-Sheet l INVENTORS.

z x l 0 HM afi MG 5 We Q Q 4 Mia Faiented ec. ii, 1945 enact CONTROL FOR REFRIGERA'JIIHI'G SYSTEMS 1 Arthur C. Hollatz and Ray G. Thomas, Bloomington, Ill., asslgnors, by mesne assignments, to Eureka Vacuum Cleaner Company, Detroit, Micln, a corporation of Michigan Application June 27, 1941, Serial No. 400,070

7 12 Claims.

This invention relates to controls for refrigerating systems and more particularly to cut-out means for the power device operating the usual compressor and in which the power device is under the control of the oil circulating system of. the compressor.

It is common practice in refrigerating systems having a compressor associated therewith to provide an oil pump driven by the compressor for circulating lubricant from a sump or other supply through the bearings and working parts of the compressor from which the oil drains back to the sump. The oil is forced through the bearings under pressure generated by the pump, and

it is an object of the present invention to provide a cut-out for the power means which cutout is controlled by the oil circulation or oil pressure in the lubricating system so that the power source will be cut off when the oil circulation pressure in the system is reduced below a predetermined value sufiicient to force the oil through the bearings.

In installations of this kind a power device such, for instance, as an electric motor is connectedin the usual manner for operating the compressor, and the motor is controlled from the refrigerating system so that predetermined variations in pressure or temperature in the refrigerating system will start and stop the motor in accordance with refrigerating requirements.

It is an object of this invention to provide an additional control operable by variations in the oil circulating system of the compressor so that, when the oil pressure drops below a predetermined valu required for proper lubrication, or

when for any reason there is not a proper circulation of lubricant, the motor and associated compressor will be stopped, irrespective of the refrigerating system control of the motor. In other words, the oil control device is a master control over the motor controlling means of the refrigerating system. v i

It is desirable that, when the refrigerating system starts the motor, the motor should run a sufficient length of time to determine whether or not the proper circulation of lubricant will be obtained in the compressor lubricating system.

.If for any reason the oil does not circulate or the proper pressure is not generated, then the motor should stop until the supply of oil has been renewed or proper repairs made to assure the generation of suiflcient pressure 'to force the oil through the working parts of the compressor. If the oil is properly circulated, then the motor circuit should remain closed so that the compressor may continue to operate in th usual manner until the refrigeration control again stops the motor. It is therefore an object of the present invention to provide a master cut-out for the power means of a refrigerating system in which normal operation of the power means and associated compressor is determined by variations in the oil circulating system of the compressor; also in which th normal operation of the refrigeration control of the power means is allowed to function in the usual manner until the condi-.

tion of the oil circulating system of the compressor is automatically determined. at which time, if the oll circulation is insumcient properly to lubricate the compressor, the power means will be cut off, irrespective of the refrigerating control therefor.

control system.

Further objects will be apparent from the specification and the appended claims.

In the drawings:

Fig. 1 is a somewhat diagrammatic view of a compressor and, control system therefor.

Fig. 2 is a fragmentary sectional view of the control device shown in Fig. 1 and. illustrates a latch for the thermostatic control switch.

Fig. 3 is a view similar to Fig. 1 but illustrates a somewhat diflerent embodiment of the Fig. 4 is a transverse sectional view through the resetting switch shown in Fig. 3 and is taken on a line substantially corresponding to line 4-4 thereof.

Referring to the drawings in detail, the embodiment illustrated in Fig. 1 comprises a comsystem to which it is connected by means of the conduits l and 2 and is provided with an oil sump 4. An oil pump 5 is mounted on the crankcase and operated by the crankshaft 3' or other suitable means to pump oil from the sump 4 through a conduit 6 and through suitable channels into the working parts of the compressor. The oil then drains into the crankcase and downwardly through a suitable conduit 1 into the sump, thus providing an oil circulating system controlled by the pump 5.

A motor 8 is arranged to drive the compressor in the usual manner and by any suitable transmission, not shown. The motor 8 is provided with a power circuit comprising the conductors 9 and it, which may be controlled by means of a main switch ll.

The usual automatic start and stop switch I2 is in series with the motor,

' and this switch may be any of the usual types of temperature or pressure controlled switches such as are commonly associated with the refrigerating system of the usual refrigerator to intermittently operate the motor in accordance with refrigerating requirements.

A thermostatic switch I3 is also in series with the switch l2 and the motor 8 and also in series with a heater resistance i4 which completes a temporary power circuit through the conductors 9 and I as shown. This heater resistance I4 is designed to carry suflicient current to operate the motor 8 and is so associated with the therconduit I'I. An expansible and contractible bellows I8 is mounted in the casing in a manner to provide a pressure chamber l9 therein. A stem 20 is secured to the free end of the bellows and extends upwardly into a switch casing 2 l A compression spring 22 is supported in the bellows l8 and tends to expand the bellows against the oil pressure in the chamber i9. An arm 23 is pivoted at 24 in the switch casing 2| and rests on the end of the stem 20. A mercury switch 25 is mounted on the arm 23 and is provided atone end with the usual contacts 26, which contacts are normally open but are closed by mercury in the usual manner when the arm 23 is raised under the compressionof oil in the chamber i9 against the bel-' lows. A stop 21a is provided for the arm 23 so that, when the arm and switch thereon are in the raised position against the stop, the mercury switch will be closed. The mercury switch is shunted across the resistance M by means of the conductors 21. It will be apparent that, when the mercury switch 25 is closed, the conductors 21 shunting the resistance carry sufllcient current so that the resistance I4 will not be heated and the temperature will not rise sufflciently in the switch casing to cause the thermostatic switch l3 to open the circuit. Therefore, the motor and compressor will continue to run until they are stopped by the refrigeration control switch l2 in the usual manner.

switch i 3 to break the circuit and stop the motor.

Also, if at any time during the normal running of the motor the pressure in the bellows chamber l9 drops below a predetermined value, then' the mercury switch 25 will break its shunt circuit and the resistance l4 will then heat up sumciently to'cause the thermostatic switch l3 to open the circuit'and stop the motor. v

Fig. 2 illustrates a latch device which may be applied to the structure illustrated in Fig. 1 for retaining the thermostatic switch I3 in open position after the circuit is broken and until it is desired to reset it for further automatic control. A- latch 28 is pivoted at 29 and provided with a push button 30 for resetting the switch. A spring 3| tends to retain the latch in the position shown.

When the thermostatic element i3 is heated suiiiciently to break the circuit, it will be engaged by thelatch 28 and retained in open position until it is reset by manual pressure on the push button 30.

Figs. 3 and 4 illustrate another embodiment of the invention in which the compressor, the powermeans, and the refrigeration control switch and circuit therefor may be substantially identical with that previously described. In this embodiment an oil circulating conduit 32 leads from the sump 4 into a heater casing 33 having an elongated heater chamber 34 therein. The oil from the sump circulates through a conduitextension I 35 to the inner end of the heater casing 33, as illustrated, and returns to the pump 5 through a conduit 36 leading from adjacent the outer end of the heating chamber.

The inner end'of the heater casing 33 extends into a switch casing 31, as shown, and this inner end is provided with a thin-walled cylindrical portion 38 adapted to easily conduct heat therethrough. A cover 39 is rotatably mounted on the end of the heater casing 33 in a manner to provide an annular chamber therebetween, which chamber contains a normally solid annular body 40 of an easily fusible metal, such, for instance, as soft solder. A heater element II is wound around the so-called solder pot and is connected in series with the motor 8, the refrigeration control switch i2, and with a resetting switch, the latter including terminals 42 and a switch arm 43. The switch arm 43 is resiliently supported on a-push button 44 and is normally urged toward switch closing position by means of a spring-45.

The push button 44, including the switch arm 43,

is normally urged upwardly by means'oi a heavier spring 46. The push button is provided with a flexible ratchet pawl 41 secured thereto, the upper end of the pawl being in engagement with a ratchet wheel 48 forming a part of the solder pot member 39. It will be apparent thatt as long as the solder 40 is solid, the switch will be retained in the closed position shown by means of the ratchet and pawl, and, when the solder is fused, the spring 46 will operate to rotate the solder pot element 39 and thereby permitthe switch to open.

The automatic flow controlled device may be connected to either the pressure or suction side of the pump and the oil connections made accordingly. The successful operation of the device depends upon the circulation of the oil and not upon the location of the control device in any particular part of the circulating system.

In operation, as long'as there is sufficient circulation of oil through the system, this circulation through the chamber 34 will keep the solder pot sufllciently cool so that the heater element 4| will not melt the solder. However, if, for any reason, the circulation is stopped or sufllciently reduced in the chamber 34, the temperature will quickly rise in the solder pot to a degree which will melt the solder and, allow the member 39 to be rotated by the pawl 41 and thereby automatically open the switch and stop the motor and associated compressor.

said motor in accordance with refrigerating requirements, said compressor having an oilcirculating system, a normally closed switch in the power controlling circuit of said motor, resilient means tending to open said switch, fusible metal means in heat conductive relationship to an oil circulation conduit of said circulating system to make said resilient means ineffective to open said switch, and a heater for fusing said metal to permit said switch to open, said heater being normally of insufficient capacity to fuse said metal when the oil circulation is maintained at a predetermined normal speed and suiiicient to fuse said metal and release said switch when the oil circulation drops below said normal.

2. In a refrigerator having the usual compressor and motor for driving the same and means to cause automatic operation of said motor in accordance with refrigerating requirements, said compressor having an oil circulating system, a normally closed switch in the power controlling circuit of said motor, means tending to open said switch, fusible means closely associated with an oil circulation conduit of said circulating system to normally make said last means ineffective to open said switch, a heater operable to transmit heat to said fusible means when said motor circult is closed, said fusible means being sufficiently closely associated with said oil circulating system so that sufficient heat is normally conducted .from said fusible means to prevent fusing only when a predetermined circulation flow is maintained.

3. In a refrigerator having the usual comprestor and motor for driving the same and means to cause automatic intermittent operation of said motor, in accordance with refrigerating requirements, said compressor having an oil circulating system, a normally closed switch in the power controlling circuit of said motor, resilient means tending to open said switch, fusible metal means in heat conductive relationship with a conduit of said oil circulating system and forming a detent normally holding said switch closed, and a heater for fusing said metal to thereby release said switch, the heat conductive relationship of said fusible metal to the oil in said conduit being such as normally to permit melting of said metal only when oil circulation is retarded below a positioned to fuse said metal to thereby release tioned in a heat conductive relationship to a conduit of said oil circulating system that said heater is normally effective to melt said metal only when said oil circulation is retarded below 1 a predetermined speed, and means to reset said switch relative to said movable member after said metal hardens.

5. In a refrigerator having the usual compressor and motor for driving the same and-means to start and stop said motor. said compressor having an oil circulating system, a normally closed switch in the power controlling circuit of said motor, resilient means tending to open said switch, fusible metal means in heat conductive relationship to an oil circulation conduit of said circulating system to make said resilient means ineffective to open said switch, and a heater for fusing said metal to permit said switch to open, said heater being normally of insufficient capacity to fuse said metal when the oil circulation is maintained at a predetermined normal speed and sufficient to fuse said metal and release said switch when the oil circulation drops below, said normal speed.

6. The device recited in claim 5 wherein said heater comprises an electrical resistance in said circuit in'series with said normally closed switch.

7. The device recited in claim 5 including means to reset said switch after the fused metal hardens.

8. In a power operated device, an operative mechanism, a motor for driving the same and circuit control means in the motor circuit to start and stop said motor, said operative mechanism having an oil circulating system, a normally closed switch in the power controlling circuit of said motor. resilient'means tending to open said switch, fus ble metal means in heat conductive relationship to an oil circulation conduit of said circulating system to make said resilient means ineffective to open said switch, and a heater for fusing said metal to permit said switch to open, said heater being normally of insufficient capacity to fuse said metal when the oil circulation is maintained at a predetermined normal speed and sufficient to fuse said metal and release said switch when the oil circulation drops below said normal speed.

9. In a refrigerating system having a compressor, driving means therefor and means to cause automatic intermittent operation of said compressor in accordance with refrigerating requirements, said compressor having an o l circulating system, the combination of thermal responsive control means for stopping said compressor independently of said automatic means, said control means including a thermal responsive element in heat conductive relation to a portion of said oil circulating system, and heating means for said thermal element so proportioned that the heat supplied to said thermal responsive element is normally insuflicient to effect operation of said control means when the oil circulation exceeds a predetermined rate of flow and is sufllcient to effect operation thereof to stop said compressor when the oil circulation falls be- I low said predetermined rate.

10. In a refrigerating system having a compressor, driving means therefor and means to cause automatic intermittent operation of said compressor in accordance with refrigerating requirements, said compressor having an oil circulating system, the combination of thermal responsive control means for stopping said comprcssor independently of said automatic means. said control means including a thermal responsive element in heat conductive relation to a portion or said oil circulating system, and heat-' ing means for/said thermal element, "said heat conductive relation being such as normally to permit sufllcient heating of said thermal responsive element to operate said control means only when the oil circulation falls below a predetermined rate of flow. 7

11. In a refrigerating system having a compressor, an electric driving motor therefor, and automatic means for starting and stopping said motor in accordance with refrigerating requirements, said compressor having an oil circulating system, the combination of thermal responsive switch means for stoppingsaid motor independently of said automatic means, said switch means including a thermal responsive element in heat conductive relation to a portion of said oil circulating system, and heating means for said thermal responsive element energizable upon closure of said automatic means, said heating means being proportioned so that the heat supplied to said thermal responsive element normally is insufllcient to eilect operation of said switch means when the oil circulation exceeds a predetermined rate or flow and is suilicient to eii'ect operation thereof to stop said motor when the oil circulation falls below said predetermined rate.

12. The combination with an operative mechanism, a motor for driving the same. and means responsive element in heat conductive relation to I a portion of said oil circulating system, and heating means for said thermal responsive element energizabie upon closure of said switch means,

a said heating means being so proportioned as nor- ARTHUR c. HOLLA'IZ.

RAY G. THOMAS. 

